Record

Learn tuples with Dart 3 Records.

Records as tuples

Dart 3 Record type bundles several values into one package. For example (int, String) p = (42, 'Dart'); declares a record. Each item in parentheses is a field.

You can access fields by position: p.$1 gives the first value (42), p.$2 the second (Dart). Indexes start at 1.

Records are immutable. Two records with the same fields and values are equal. So records are ideal for carrying data.

Named fields

Records can have named fields alongside positional ones. Example: ({String name, int age}) p = (name: 'Alex', age: 30);. Here you access p.name and p.age.

Named fields are written inside curly braces and accessed by name. Positional fields are accessed with $ indexes.

A record can hold both: (int, {String label}). This flexibility lets you express data structures clearly.

Exercise A positional record

In main declare (int, String) p = (7, 'Dart');. Print p.$1 and p.$2 on separate lines with print.

Show example solution

void main() {
  (int, String) p = (7, 'Dart');
  print(p.$1);
  print(p.$2);
}

Test yourself

Accessing a record field

var p = (42, 'Dart');
print(p.____);

Show answer

var p = (42, 'Dart');
print(p.$1);

What is true of records?
- They are mutable
- They take only two fields
- They replace classes
- Two equal records are equal
Show answer

Two equal records are equal — two records with the same fields and values are equal.
Match the record parts

(42, 'Dart')

Positional record
(name: 'Alex', age: 30)

Named record
p.$1

First positional field
p.name

Named field

Next lesson: Pattern matching

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